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Published on: April 9, 2016
Production of a bioflocculant by Aspergillus parasiticus and its application in dye removal
Shubo Deng1, Gang Yu, Yen Peng Ting
1Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, PR China.
Abstract:
Aspergillus parasiticus was found to produce a bioflocculant with high flocculating activity for Kaolin suspension and water-soluble dyes. Results showed that the carbon and nitrogen sources favorable for the production of the bioflocculant were corn starch and peptone, and an optimal condition of 28 degrees C, initial pH 5-6 and shaking speed of 150 rpm. The highest flocculating efficiency achieved for Kaolin suspension was 98.1%, after 72 h cultivation. The bioflocculant was mainly composed of sugar (76.3%) and protein (21.6%), and an average molecular weight of 3.2x10(5) Da. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectra showed that amino, amide and hydroxyl groups were present in the bioflocculant molecules. The bioflocculant was effective in flocculating some soluble anionic dyes in aqueous solution, in particular Reactive Blue 4 and Acid Yellow 25 with a decolorization efficiency of 92.4 and 92.9%, respectively. The decolorization efficiency was dependent on the flocculant dosage and solution pH. XPS result shows that the amine groups in the bioflocculant were protonated at pH 5, and thus the positive bioflocculant was attracted to the negatively charged dye molecules. The amino and amide groups in the bioflocculant molecule are believed to play an important role in flocculation from the viewpoint of electrostatic interaction.
Insights
Aspergillus parasiticus produces a bioflocculant effective for Kaolin suspension and dye decolorization. Optimal production conditions and key molecular components were identified, highlighting its potential in water treatment applications.
Area of Science:
- Microbiology
- Biotechnology
- Environmental Science
Background:
- Microbial bioflocculants offer a sustainable alternative to chemical flocculants.
- Aspergillus parasiticus is known for producing various metabolites, but its bioflocculant properties require further investigation.
Purpose of the Study:
- To identify and characterize a bioflocculant produced by Aspergillus parasiticus.
- To determine optimal conditions for bioflocculant production.
- To evaluate the bioflocculant's efficacy in removing Kaolin suspension and decolorizing anionic dyes.
Main Methods:
- Cultivation of Aspergillus parasiticus with varying carbon and nitrogen sources.
- Optimization of fermentation parameters (temperature, pH, shaking speed).
- Characterization of bioflocculant composition and molecular weight using spectroscopy (XPS, FTIR).
- Assessment of flocculation efficiency for Kaolin suspension and decolorization efficiency for Reactive Blue 4 and Acid Yellow 25.
Main Results:
- Optimal bioflocculant production achieved using corn starch and peptone at 28°C, pH 5-6, and 150 rpm, yielding 98.1% Kaolin suspension flocculation.
- The bioflocculant consists mainly of sugar (76.3%) and protein (21.6%) with a molecular weight of 3.2x10^5 Da.
- High decolorization efficiencies of 92.4% for Reactive Blue 4 and 92.9% for Acid Yellow 25 were observed, dependent on dosage and pH.
- XPS analysis indicated the presence of amino, amide, and hydroxyl groups, crucial for electrostatic interactions with anionic dyes.
Conclusions:
- Aspergillus parasiticus produces a potent bioflocculant with significant potential for water and wastewater treatment.
- The bioflocculant's effectiveness is linked to its composition, particularly amino and amide groups, and optimal environmental conditions.
- Further research into the bioflocculant's application and mechanism can lead to eco-friendly water purification strategies.
